Evaluation of biological response induced by molybdenum oxide nanocolloids on in vitro cultured NIH/3T3 fibroblast cells by micro-Raman spectroscopy.

Tailored colloids of uniformly sized and engineered molybdenum oxide nanoparticles were produced, for the first time, by pulsed laser ablation in water. This green technique ensures the formation of contaminant-free nanostructures and the absence of by-products, very useful issues in biological applications. A selective tuning of MoO chemical bonding configurations and a suitable control of nanoparticles size distributions were achieved during the ablation processes by varying the water temperature and by applying an external electric field. The metal redox properties are fundamental factors governing both cell uptake and interaction mode with Mo oxide nanoparticles. Micro-Raman spectroscopy was used to investigate the existence of cellular changes induced by Mo oxide colloids on the fibroblast cell line NIH/3T3 in relation to the molecular vibrations due to proteins, lipids and nucleic acids. The label-free micro-Raman spectroscopy provides an easy and noninvasive method to monitor the harmful effect of toxic agents on cells through ROS production or redox-dependent mechanisms. In view of potential biological applications, molybdenum oxide nanoparticles cytotoxicity towards NIH/3T3 cells was also investigated. A statistical analysis shows that, in the 10-100 μg/mL Mo concentration range, all the colloids are cytotoxic, progressively reducing the cell viability down to 75% upon increasing the concentration. The effect is less pronounced for the oxygen deficient MoO3 samples where cell viability does not fall below 85%. These results open the way to identify potential bioactive products affecting cellular redox status, by using only the Raman spectral data, even before performing lengthy and expensive specific clinical analyses.